Yamaha PC2002 User manual

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PROFESSIONAL

SERIES

POWER

AMPLIFIER

PC2002/2002M

OPERATING

MANUAL

THEAMAL

2

FEN

eas

m

“ум.

D

ym

е

о

10:

50

2

P

PO

ор

2

as

PROTECTION

510.

60

СНА

gover

19

90

2

ММА

АИ

PROTECTION

©

VIDT,

CHB

4

а

pov

ot

2

15511117

M

P

”

CHANNEL

А

CHANNEL

В

и

"om.

v

ra

ZZ

за

vip,

гр

^

YAMAHA

ABOUT

THIS

MANUAL

SCOPE

The

PC2002M

is

a

system

oriented

amplifier,

made

to

be

used

in

conjunction

.with

mixers,

consoles,

frequency

dividing

networks

and

speakers

—

those

made

by

Yamaha

or

by

other

manufacturers.

Like

any

power

amplifier,

the

PC2002M’s

performance

depends

on

system

design

and

installation,

in

addition

to

its

own

capabilities.

Thus,

the

PC2002M

Operating

Manual

is

system

oriented,

describing

system

design

parameters

and

installation

techniques,

as

well

as

operation

and

performance

of

the

PC2002M.

ORGANIZATION

We

recommend

that

you

read

the

entire

Operating

Manual.

However,

if

you

are

using

the

PC2002M

in

an

existing

system,

and

you

are

familiar

with

high

power

amplifiers,

the

BRIEF

OPERATING

INSTRUCTIONS,

Pages

2

&

3,

contain

all

the

information

necessary

for

basic

connections

and

operation.

NOTE:

The

PC2002

is

identical

to

the

PC2002M

except

there

are

no

Peak

Reading

Meters.

CONTENTS

1МТВОООСТОМ.........................

1

BRIEF

OPERATING

INSTRUCTION

...........

2,3

GENERAL

SPECIFICATIONS

................

4

PERFORMANCE

GRAPHS

..................

5,6

A

DISCUSSION

OF

SPECIFICATIONS

........

7~9

MOUNTING

.........

SW

exp

A

M

oe

E

10

BLOCK

DIAGRAM

.......................

11

DIMENSIONS

..................

а

12

INTRODUCTION

The

PC2002M

is

not

just

"another

big

amplifier”,

it is

an

exciting

new

approach

to

high

power

sound.

Yamaha's

leadership

is

clearly

demonstrated

by

the

PC2002M's

pro-

fessional

features,

sophisticated

design,

and

uncompromis-

ing

performance.

|

:

PEAK

READING

METERS*

Instead

of

the

more

common

and

slow

responding

VU

meters,

the

PC2002M

has

PEAK

READING

METERS

that

accurately

display

a

full

five

decades

(50dB)

of

output

level.

The

peak

meters

have

large,

illuminated

faces

marked

with

dB

and

with

watts

into

8

ohms.

The

fast

responding

meters

provide

a

better

way

to

see

the

program

dynamics,

the

transient

power

demands

placed

on

the

system,

and

the

available

headroom.

By

indicating

headroom,

the

meters

help

the

operator

avoid

over-driving

the

system,

thereby

preventing

the

“clipped”

waveforms

so

dangerous

to

drivers

and

loudspeakers.

:

CALIBRATED

INPUT

ATTENUATORS

The

PC2002M

has

log-linear

INPUT

ATTENUATORS

to

complement

its

peak

reading

meters.

The

input

attenuators

are

marked

in

20dB-calibrated.

steps,

detented

for

extra

accuracy.

The

attenuators

provide

a

smooth,

noise

free

transition

from

the

highest

to

the

lowest

audio

level.

dB-

calibrated

input

attenuators

have

numerous

advantages:

on

the

road,

they

allow

predictable

and

repeatable

setups;

in

commercial

sound

applications,

they

allow

easy,

accurate

input

sensitivity

adjustments;

in

studios

or

discos,

they

let

operators

simultaneously

adjust

the

level

of

two

channels

(or

two

programs

on

separate

amplifiers)

with

precise

track-

ing.

INPUT

AND

OUTPUT

CONNECTIONS

INPUT

CONNECTORS

for

each

channel

include

one

“male”

and

one

"female"

XLR

connector

(BALANCED)

plus

two

parallel

phone

jacks

(UNBALANCED).

This

provides

the

flexibility

necessary

for

convenient

bridging

to

another

amplifier,

as

well

as

for

adapter-free

connection

to

almost

any

mixer,

MONAURAL

OPERATION

The

PC2002

and

PC2002M

can

easily

be

adapted

for

monaural

(BTL)

operation

by

setting

the

rear-panel

MODE

switch

to

MONO.

In

the

MONO

mode

use

the

channel

A

input

connectors

and

channel

A

attenuator

for

level

control.

The

"+"

terminal

of

the

speaker

system

is

con-

nected

to

the

channel

А

“+”

output

terminal

and

the

“—’’

terminal

of

the

speaker

system

is

connected

to

the

channel

B

"+"

output

terminal.

Leave

the

channel

A

and

B

"—"

output

(SPEAKER)

terminals

and

channel

B

input

terminals

unconnected.

SPEAKER

IMPEDANCE

IS

16

—

32

OHMS

FOR:

MONO

MODE

OPERATION..

POUR

LE

MODE

MONAURAL

—

L'IMPEDANCE

DES

HAUT-PARLEURS

EST

16

—

32

OHMS.

MODE

ое

STEREO

МОМО

INPUT

channel.

A

PERFORMANCE

The

PC2002M’s

performance

is

as

impressive

as

its

features.

At

a

sustained

output

of

240

watts

into

8

ohms

(for

each

channel),

there

is

plenty

of

punch

to

reproduce

the

power-

ful

peaks

essential

to

clean

studio

monitoring.

High

power

handling

also

makes

the

PC2002M

an

unbeatable

choice

for

live

rock

or

disco

sound

systems,

where

an

amplifier

can

really

“cook”

all

night

long.

Power

alone

is

no

virtue;

the

PC2002M

has

ultra-low

distortion,

less

than

0.0596

THD

at

full

rated

power

—

the

kind

of

low

distortion

that

is

un-

detectable

by

even

the

most

critical

listeners.

A

high

damping

factor

of

better

than

350

at

1kHz

reduces

the

tendency

for

speaker

cone

overshoot,

giving

tighter

and

better

defined

bass

response.

On

the

other

end,

the

PC2002M's

frequency

response

extends

well

beyond

50kHz,

enabling

it

to

accurately

reproduce

the

most

complex

musical

waveforms

—

even

the

tortuous

output

of

today's

synthesizers.

However,

high

frequency

response

has

not

been

achieved

at

the

expense

of

stability;

in

fact,

the

PC2002M

is

rock

steady.

Even

when

connected

to

highly

reactive

multi-speaker

loads,

there

is

no

tendency

to

shut

down

or

“take

off”

into

spurious

oscillation.

MECHANICAL

CONSIDERATIONS

The

PC2002M

is

constructed

to

withstand

the

high

"G"

forces

encountered

on

the

road.

Its

solid

front

panel

mounts

in

any

standard

19-inch

rack,

and,

for

a

large

amplifier,

the

PC2002M

weighs

a

modest

44

pounds

(20.5kg).**

Front

panel

controls

and

meters

are

recessed

to

avoid

damage

or

accidental

setting

changes,

and

are

further

protected

by

a

pair

of

sturdy

carrying

handles.

Inside

and

out,

the

PC2002M

is

extremely

reliable.

Still,

should

service

ever

be

required,

the

unit

is

designed

for

easy

access.

Massive

side-mounted

heat

sinks

are

designed

for

efficient

cooling,

making

fans

unnecessary

in

all

but

the

most

severe

thermal

operating

conditions.

Four.

non-conductive

feet

ensure

proper

air

flow

when

the

amplifier

is

shelf

mounted,

and

avoid

inadvertent

ground

loops.

Multiple

protection

circuits

make

the

amplifier

nearly

abuse

proof

and

eliminate

the

need

for

troublesome

DC

power

supply

fuses.

*

The

PC2002

does

not

have

the

Peak

Reading

Meters.

**

The

PC2002

weighs

44

pounds

(20kg)

BRIEF

OPERATING

INSTRUCTIONS

e

Front

panel

ө

Rack

Handle

THERMAL

PROTECTION

CHB

Rack

Handle

|

:

|

"ew

|

|

|

5

50

зоо

in

N

|

ПИР

ДЕҢ

4

ҮР,

PEAK

ағ

WATTS

ДИ

ө

soo)

10

60

50

по

;

f

\

Мур

2

5

POWER

PUSH

ON/PUSH

OFF

YAMAHA

PROFESSIONAL

SERIES

POWER

AMPLIFIER

MODEL

@

POWER

Switch/Indicator

Pressing

this

switch

turns

power

to

the

amplifier

ON

and

causes

the

power

indicator

to

light.

Pressing

the

POWER

switch

a

second

time

turns

the

unit

OFF.

@

THERMAL

Indicator

This

indicator

lights

if

surface

temperature

of

the

main

heat

sink

exceeds

85

+

5

degrees

centigrade.

Ө

PROTECTION

Indicator

Lights

for

approximately

4

seconds

after

power

is

switched

on,

indicating

that

the

protection

circuitry.

is

active.

The

speaker

outputs

are

shut

off

while

this

indicator

is

lit.

If

the

protection

circuitry

is

activated

for

any

reason

during

amplifier

operation,

the

indicator

will

light

and

the

speaker

outputs

will

be

shut

off.

Once

the

cause

of

protection

activation

has

been

remedied

normal

operation

will

resume

automatically

and

the

protection

indicator

will

go

out.

Ө)

PEAK

Level

Meters

(PC2002M)

These

meters

have

a

rise

time

of

10

milliseconds.and

a

fall

time

of

0.8

seconds.

The

logarithmic

meter

scales

read

directly

in

watts

when

speaker

impedance

is

8

ohms.

A

dB

scale

is

also

provided

with

O

dB

referenced

at

100

watts.

211908

"RU

ust

ба

в‘

~

a?

s

CHANNEL

А

CHANNEL

В

.

9

an

8

@

Accessories

Fig.

1.

©

CLIP

Indicator

|

The

CLIP

indicators

light

when

output

distortion

of

the

respective

channel

exceeds

approximately

2%.

This

indicates

that

the

amplifier

is

clipping

due

to

excessive

input

signal

levels.

|

*The

PC2002

CLIP

indicators

are

located

above

the

input

attenuators.

О

Zero

Adjust

(PC2002M)

A

small

“*—''

screwdriver

is

used

to

adjust

the

peak

meter

zero

point.

@

Input

Attenuators

The

controls

are

detented

in

21

dB

steps,

each

step

cor-

responding

to

1

dB

of

attenuation

except

the

last

step.

Attenuation

in

the

fully

clockwise

position

is

О

dB,

and

co

in

the

fully

counterclockwise

position.

Q

Knob

Lock

Adaptors

(Supplied)

The

Knob

Lock

Adaptors

prevent

accidental

alteration

of

attenuator

settings

once

the

appropriate

settings

have

initially

been

made.

Веаг

рапе!

Cord

Reel

|)

SIEREO

МОМО

МАХАМ

SP

MRIG

USED.

CAUTION

то

REDUCE

THE

RISK

OF

ELECTRIC

SHOCK,

DO

NOT

REMOVE

COVER

HO

USER

SERVICEABLE

PARTS

INSIDE

PROT

LAMP

SOLOERED

IN

PLACE.

REFER

SERVICING

TO

QUALIFIED

SERVICE

PEAS

ATTENTION

afin

DE

RÉOUIRE

LE

RISQUE

Hi

ЕЗ

EON.

Ms

ENLEVER

LE

COUVERCLE.

IL

NE ЗЕ

TROUVE

A

СМТЕВЕУЯ

Al

POUVANT

ETRE

БЕРАНЕ

PAR

LUSAGER.

LA

LAMPE,

ТЄМОН

EST

SOUDGE

EN

PLACE.SAORESSEA

А

UN

REPARATEUR-

СОМРЕТЕ!

WARNING

то

nebuce

тне

Te

О

OF

FIRE.

г

сию

‘SHOCK,

DO

мог

EXPOSE

THIS

APPLIANCE

TO

RAN

ОН

MOISTURI

CAUTION

то

ЕЕ

due

FISK

OF

FIRE,

REPLACE

чат

SAME

TYPE

FUSE,

0

ATTENTIONS

эни

DE

А

RÉDUnE

LE

RISQUE

DE

FEU,

REMPLACE!

LUNQUEMENT

PAR

VW

FUSLE

PRIMARY

{е

7A

1250

«95,

х

US

4

Canadian

models

YAMAHA

General

model

@

SPEAKER

Output

Terminals

Fig.

2

The

red

SPEAKER

terminal

is

connected

to

the

“+”

input

©

Standard

Phone

Jacks

terminal

of

the

speaker

system

used

and

the

black

These

jacks

accept

unbalanced

input

via

standard

1/4”

SPEAKER

terminal

is

connected

to

the

"—"'

speaker

input

phone

plugs.

The

BALANCED/UNBALANCED

switch

terminal.

|

should

be

set

to

UNBALANCED

when

using

these

inputs.

These

jacks

can

also

be

used

as

send

terminals.

Ө

PIN

1GND

SW

Couples

or

decouples

the

canon

connector

earth

line

(pin

1,

о

BALANCED/UNBALANCED

Switch

shield).

Normally

ON.

In

some

cases

where

ground

loops

Determines

which

input

connectors

are

active.

In

the

cause

excessive

hum,

turning

the

ground

switch

OFF

can

BALANCED

position,

input

signals

are

accepted

via

the

interrupt

the

loop

and

reduce

the

hum.

balanced

Canon

connectors,

and

in

the

UNBALANCED

position

input

is

accepted

via

the

unbalanced

phone

jacks.

Ө

Canon

Connectors

(XLR-3-31)

These

connectors

are

generally

used

as

inputs.

Pin

1

is

@

MODE

Selector

Switch

shield,

pin

2

is

hot

and

рт

3

cold.

Compatible

connectors

Determines

whether

the

amplifier

is

to

operate

in

the

stereo

include

Canon

XLR-3-12C

and

Switchcraft

5C-1055A.

or

mono

(BTL)

mode.

©)

Canon

Connectors

(XRL-3-32)

Compatible

with

Canon’

XLR-3-11C

ог

switchcraft

5C-1056A

connectors,

these

connectors

are

useful

for

send-

ing

the

input

signal

to

other

power

amplifiers.

+ |

—

ыюъмы

‚АА

=

:

GENERAL

SPECIFICATIONS

о

а

с

POWER

OUTPUT

LEVEL

Continuous

average

sine

wave

power

with

less

than

0.05%

THD.

20

Hz

to

20

kHz.

Stereo,

8ohms.........

ip

UIS

240W

+

240W

Mone,

16

оћтѕ

....................

480W

Mono,8ohms

......................

700W

FREQUENCY

RESPONSE

10

Hz

to

50

kHz,

8ohms,

1М/............

2058

POWER

BAND

WIDTH

Stereo

8

ohms

120W

THD

ОМ

Фа

а

а

ылыы

10

Hz

to

100

kHz

Mono

16

ohms

240W

THD

0.1%

.....

ани

10

Hz

to

100

kHz

TOTAL

HARMONIC

DISTORTION

Stereo

8

ohms

120W

TkHz...................

Less

than

0.003%

Mono

16

ohms

240W

|

20

їо

20

КН2

..............

Less

than

0.007%

Mono

8

ohms

350W

201020КН2...............

Less

than

0.01%

INTER

MODULATION

DISTORTION

70

Hz

7kHz

mixed

4:

1

Stereo

8

ohms,

120W

.........

Less

than

0.01%

Mono

16

ohms,

240W

.........

Less

than

0.01%

INPUT

SENSITIVITY

Input

level

which

produces

100W

output

into

8

ohms

tate

Seg

E

A

EEES

0

dB

(0.775

V

rms)

INPUT

IMPEDANCE

Balanced

and

unbalanced

inputs,

maximum

attenuator

setting

..............

TD

25

kohms

8

OHM

DAMPING

FACTOR

КА

и

vas

vei.

Greater

than

350

201020КН2...............

Greater

than

200

S/N

RATIO

Input

shorted

at

@12.47

kHz

............

110

dB

Input

shorted

at

@IHFA

...............

115

dB

SLEW

RATE

Stereo8ohms

...................

60

V/usec

Mono

1боһтз...................

90

V/usec

CHANNEL

SEPARATION

8

ohms

120W

ТКН

pM

Mn

TL

95

dB

8

ohms

120W

201020КН2,............

MORE

80

dB

RELAY

MUTING

TIME

42

From

power

on

...................

have

4

14

sec

INDICATORS

РОМЕ

ON

и

Cosy

Дыл

АКУ

шга

кылы

LED

Protection

(Relay

OFF)

..................

LED

Thermal

Overload

(85

+

5

degrees

C)

.........

LED

Clipping

(2%

THD)

................

шил

ТЕР

Peak

Power

Meters

(PC2002M

only)

. .

.

—50

dB

to

+50

dB

range

O

dB

=

100W

into

8

ohms

FRONT

PANEL

CONTROLS

Power

буйсн...............

Push-ON/Push-OFF

Input

Attenuators

(one

per

channel)

гэгээ

22

detent

positions

in

—1

dB

steps

(0,

—1,—2...-—20,

®)

REAR

PANEL

CONTROLS/CONNECTORS

Mode

switch

.................

STEREO/MONO

Pin

1

GND

Switch

(XLR

connectors)

,.....

ON/OFF

Balance/Unbalance

Switch

.....

BALANCED

(XLR)/

UNBALANCED

(PHONE)

POWER

REQUIREMENTS

U.S.

&

CANADIAN

models

...

....

AC120V,

60

Hz

GENERAL

Model.........

АС220/240\,

50/60

Hz

POWER

CONSUMPTION

|

U.S.

8

CANADIAN

models

..............

700

W

GENERAL

тоде!..........

РОА

1600

W

DIMENSIONS

(үх

рхнН)...............

480

х

413

х

183

тт

(18-7/8"

х

16-1/4"

x

7-1/4”)

WEIGHT

PC2002

араа

аа

каа

Ми

20

kg

(44

pounds)

РС2002М

.................

20.5

kg

(45

pounds)

NOTE:U.S.

8:

CANADIAN

Models

must

be

operated

into

8

ohms

in

stereo

mode

and

16

ohms

in

mono

mode

in

accordance

with

safety

regulations.

All

specifications

subject

to

change

without

notice.

PERFORMANCE

GRAPHS

[27]

пина

и

1000

:

оов

$ Я

бог

Be

H

оо!

===

.

0005

=I

a

-

Г

Fig.

3

зоо

нЕ

Fig.

7

Io!

ооо!

5

^

5

LOAD

IMPEDANCE

Bor

mnm

о:

02

os

а

2

оџтрот

POWER”

so

юо

200

юм

LOAD

IMPEDANCE

VS

OUTPUT

POWER

T.H.

DISTORTION

THD

0,05%

Mode

STEREO

Load

Impedance

82

Single

Channel

Driven

Mode

STEREO

Both

Channel

Driven

IN/OUT

Channel

A

4-3-4---4-1----

Ш

[^]

м

1000

шини

шш

ишш

шша

=

ог

m

3

ЫГ

Ф

ол

|

300

|

оов

==

gro

@

|

Бо

ЕЕН

T

ЕН

Зоог

20

|

Fig.

4

9005

ю

100

шэнжэ

ЮК

(He)

ооо

"nM

Fig.

8

POWER

BAND

WIDTH

9001

са

ог ољ

t

2

5

10

20

Бо

00

200

500

(4)

Load

Impedance

162

а а

80

OUTPUT

POWER

Mode

MONO

Mode

STEREO

Load

Impedance

162

т

Both

Channel

Driven

Mode

MONO

s

E

|

|

Г

о

кај

ш

100

аша

i-

Ф

ЦЭ

йл

ШИ

i

i

ni

5

mi

BAL

IN

-5

HH

3

20

x

>

Г]

i

lo

H

|__|

Е

IN

M

:

Г

ЕЕ:

79

Fig.

5

3

+H

юго

50

00

200

бо

Ik

әк

Sk

пок

20

50к

(HD

8

2

4-4

Fig.

9

FREQUENCY

.

FREQUENCY.RESPONSE

'

105

Nm

ТОК

UR

(D

Load

Impedance

162

@

Load

Impedance

80

INPUT

IMPEDANCE

Power

Output

Power

Output

Mode

STEREO

=

1W

at

1kHz

=

1W

at

1kHz

Mode

MONO

Mode

STEREO

Channel

A

Channel

A

&

B

(UNBAL

INPUT)

(UNBAL

INPUT)

|

|

“)

НИ

1000

H

05

|

Н

500

|-|

ЕНН

3

и

ry

8

о

71717

5

04

i

2

(00

ae

Bos

FE

Е

[У

|

г

S

вю

{=

17

0.05

й

0.02

зо

'

Fig.

10

И

|||

Fig.

6

оо

100

FneluENCY

пок

(на)

9

100

re

ute

ток

(HR)

1

OUTPUT

IMPEDANCE

DAMPING

FACTOR

|

Load

Impedance

82

Load

Impedance

82

)

|

Mode

STEREO

Моде

STEREO

The

following

are

actual

oscilloscope

photographs

made

by

an

in-

dependent

testing

laboratory.

НЕЕ

~

20

Hz

Square-Wave

Response

Remarkably

accurate

response

at

this

low

frequency

ensures

that

bass

reproduction

will

be

tight

and

clean.

рүү

ИШИШ

ЕШШ

·:

:

1

kHz

Square-Wave

Response

Flawless

midrange

response

is

immediately

evident

in

this

scope

trace.

There

is

no

unnatural

response

rolloff,

ringing

or

overshoot

to

interfere

with

music

reproduction.

Ши

сн

cutn

pea

|

|

ГГ

=:

20

kHz

Square-Wave

Response

Although

20,000

Hz

is

well

beyond

the

range

of

human

hear-

ing,

the

response

accuracy

shown

here

means

that

upper-

range

harmonics

vital

to

natural

reproduction

will

be

proper-

ly

reproduced,

||

|||

шатлан

Шин

ажи

А

Мур

А

И

|

|

7

БШ

БИШ

ШИ

-.

Total

Harmonic

Distortion

with

a

1

kHz

Sine

Wave

Signal:

The

distortion

components

shown

in

this

trace

are

actually

a

mere

0.001496,

It's

this

type

of

low-distortion

performance

that

makes

the

PC2002

and

PC2002M

ideal

for

demanding

professional

applications.

VEN

BIO

Mus.

imd.

ши

ENNENNENN

=>

Total

Harmonic

Distortion

with

a

20

kHz

Sine

Wave

Signal

Although

the

amp

is

delivering

240

watts

(mono,

BTL)

output

power

continuously

at

20,000

Hz,

harmonic

distor-

tion

is

no

more

than

0.0036%.

That

means

clean,

transparent

highs,

even

on

high-level

peaks,

Kf

МУТ

|

АУ

Шимт

дани

Шинэ

шин

РИА

МЕТ

о

-<

Slew Rate

and

Rise

Time

1

Stereo

mode,

8

ohm

load

f=2

kHz

:

GOV/uS

slew

rate

шаншаннн

Шина

А

|

У

|.

шинэ

шин

АРА

УК

Мм

|

с

--

Mono

mode,

16

ohm

load,

f=2

kHz:

90V/uS

slew

rate.

BEN

Шин

HERE

ШШЕ

Е

ШШШ

1

-

Stereo

mode,

8

ohm

load,

f=1

kHz:

1.848

rise

time.

Here's

your

guarantee

of

exceptional

transient

response.

Extremely

high

slew

rate

and

fast

rise

time

mean

precise

signal

reproduction.

[1uS/horizontal

division,

20

V/vertical

division]

А

DISCUSSION

OF

SPECIFICATIONS

POWER

OUTPUT

Types

of

Power

Ratings

Peak

power

refers

to

the

maximum

undistorted

power

output

of

an

amplifier.

Most

amplifiers

cannot

sustain

their

peak

power

ratings

for

long

periods

of

time

without

external

cooling

fans.

Because

there

are

many

different

methods

of

rating

an

amplifier's

peak

power,

it

is

hard

to

objectively

compare

the

peak

power

ratings

of

two

amplifiers.

The

peak

power

rating

is

primarily

useful

for

determining

an

amplifier’s

ability

to

reproduce

the

peaks

and

transients

in

a

musical

program,

peaks

which

may

be

20dB

or

more

above

the

average

power

level.

The

ability

to

accurately

reproduce

these

high

power

peaks

in

a

musical

program

is

one

of

the

most

important

advantages

of

the

PC2002M

as

compared

to

a

smaller

power

amplifier.

“RMS”

power

is

actually

a

misnomer

for

average

power.

Average

power

is

usually

measured

with

a

sine

wave

input

signal,

and

is

equal

to

the

amplifier’s

RMS

output

voltage

squared

and

then

divided

by

the

load

impedance.

Because

RMS

voltage

is

used

in

the

formula,

the

resulting

power

rating

is

commonly

called

“RMS

power”.

While

it

means

.the

same

as

"RMS

power",

to

be

more

accurate,

the

PC2002M

is

rated

in

watts

of

"continuous

average

sine

wave

power”,

Since

the

PC2002M

is

a

professional

power

amplifier,

not

sold

for

home

hi-fi

use,

it is

not

required

to

meet

the

power

rating

standard

set

by

the

FTC

(Federal

Trade

Commis-

sion),

a

standard

meant

for

consumer

power

amplifiers.

However,

the

PC2002M

is

measured

under

severe

condi-

tions

which

simulate

the

most

demanding

professional

usage.

Thus,

the

PC2002M

would

easily

meet

the

FTC

ratings

for

consumer

amplifiers.

In

addition,

the

PC2002M

user

has

the

benefits

of

professional

features

and

reliability.

Reasons

for

a

High

Power

Amplifier

An

interesting

characteristic

of

the

human

ear

is

described

by

the

"Webe-Fechner"

law.

In

its

general

form,

the

law

applies

to

al!

our

senses:

The

amount

of

additional

stimulus

needed

to

produce

a

perceptible

change

is

dependent

on

the

amount

of

stimulus

already

present.

In

mathematical

terms,

the

Weber-Fechner

law

suggests

that

the

human

ear

responds

to

changes

in

sound

level

in

a

logarithmic

manner.

More

simply

this

means

that

for

a

sound

to

seem

twice

as

loud,

it

requires

approximately

ten

times

as

much

acoustic

power

(and

therefore

ten

times

as

much

amplifier

power).

Thus,

the

PC2002M's

high

power

output

capabilities

are

extremely

valuable.

One

of

the

other

benefits

of

high

power

output

is

the

ability

of

the

amplifier

to

easily

reproduce

high

peak

power

transients

(which

may

be

100

times

the

average

program

power,

or

even

more).

DISTORTION

(Refer

to

Figures

7

and

8.)

|

The

PC2002M

is

designed

to

have

the

lowest

possible

dis-

tortion.

There

are

many

different

forms

of

distortion,

however,

and

comprehensive

distortion

ratings

offer

a

means

to

compare

the

performance

of

different

amplifiers.

Harmonic

Distortion,

is

characterized

by

the

appearance.at

the

amplifier

output

of

harmonics

of

the

input

waveform

which

were

not

present

in

the

original

input

waveform;

Total

Harmonic

Distortion,

or

T.H.D.

is

the

sum

total

of

all

of.

these

unwanted

harmonics

expressed

as

a

percentage

of

the

total

signal.

Harmonic

distortion,

in

an

amplifier,

can

be

created

in

any

of

several

ways.

The

Т.Н.О.

rating

of

a

power

amplifier

refers

to

creation

of

unwanted

harmonics

by

the

amplifier

during

“linear”

operation

(normal

input

and

output

levels,

impedances,

etc.).

Harmonic

distortion

is

also

created

by

"clipping",

a

form

of

"non-linear"

operation,

which

occurs

when

the

signal

level

at

an

amplifier's

input

is

high

enough

to

drive

the

amplifier

beyond

its

rated

maximum

output.

The

amplifier,

in

attempting

to

reproduce

this

signal,

reaches

its

maximum

output

voltage

swing

before

it

reproduces

the

top

of

the

signal

waveforms.

Since

the

output

voltage

cannot

rise

any

farther,

the

tops

of

the

waveform

are

"squared

off’,

or

clipped.

Clipping

distortion

adds

odd

upper

harmonics

(3rd

harmonic,

5th,

etc.)

to

the

original

signal.

(Input

clipping

would

be

similar,

where

the

input

stage

of

the

amplifier

is

overdriven

by

a

high

level

input

signal.)

The

PC2002M

has

wide

input

headroom

and

extremely

high

peak

power

output

capabilities

(headroom)

to

help

avoid

the

problems

of

clipping

distortion.

Another

form

of

harmonic

distortion

that

occurs

in

some

power

amplifiers

is

called

crossover

distortion.

*

Crossover

distortion

can

be

caused

by

improper

bias

in

the

output

transistors

of

an

amplifier.

The

amount

of

crossover

distor-

tion

stays

the

same

whether

the

signal

is

large

or

small,

so

the

percentage

of

distortion

goes

down

as

the

signal

level

goes

up.

Thus,

an

amplifier

with

crossover

distortion

may

sound

relatively

distortion

free

at

high

output

levels,

yet

sound

“fuzzy”

at

low

levels.

Some

amplifiers

have

internal

adjustments

which

enable

a

service

technician

to

control

the

amount

of

output

transistor

bias,

and

therefore

control

the

distortion.

Fig.

19A

—

Large

Amplitude

Sine

Wave

with

Crossover

(notch)

Distortion.

:

D

CE

N

Fig.

19B

—

Smailer

Amplitude

Sine

Wave

with

same

amount

(higher

96)

of

Crossover

(notch)

Distortion.

*"Crossover",

in

this

case,

refers

to

the

transition

between

the

positive

half

and

the

negative

half

of

the

output

voltage

waveform

in

a

"push-pull"

class

B

or

AB

power

amplifier:

it

has

nothing

to

do

with

the

crossover

used

to

divide

frequencies

in

a

speaker

system.

See

Figure

19.

Intermodulation

Distortion,

or

I.M.

is

characterized

by

the

appearance

in

the

output

waveform

of

frequencies

that

are

equal

to

sums

and

differences

of

integral

multiples

of

two

or

more

of

the

frequencies

present

in

the

input

signal.

The

difference

between

intermodulation

distortion

апа

harmonic

distortion

is

that

two

or

more

different

fre-

quencies

must

be

present

to

produce

intermodulation

distortion

(only

one

frequency

is

needed

for.

harmonic

distortion

to

appear),

and

that

intermodulation

distortion

products

may

not

be

harmonically

related

to

the

original

frequencies.

Like

its

harmonic

distortion

figure,

the

inter-

modulation

distortion

in

the

PC2002M

is

low

enough

to

be

virtually

inaudible

even

in

the

most

critical

situations.

FREQUENCY

RESPONSE

(Refer

to

Figure

5)

The

frequency

response

of

the

PC2002M

describes

the

variation

in

its

output

signal

level

with

frequency

when

the

input

signal

is

held

constant.

The

extremely

"'flat"

frequen-

cy

response

curve

of

the

PC2002M

is

an

indication

of

its

overall

quality

and

its

ability

to

respond

to

upper

and

lower

harmonics

of

signals

all

the

way

to

the

extremes

of

the

.

audio

spectrum.

Because

extreme

stability

is

necessary

for

some

types

of

commercial

sound

applications,

some

manufacturers

restrict

frequency

response

or

allow

relatively

high

distortion

in

return

for

increased

amplifier

stability.

The

PC2002M,

on

the

other

hand,

has

excellent

frequency

response

and

ultra-

low

distortion,

yet

is

inherently

stable

under

the

most

difficult

loads,

even

in

the

"mono"

mode.

The

frequency

response

of

the

PC2002M

has

been

inten-

tionally

limited,

however,

at

very

low

frequencies

(sub-

audio).

Because

of

this,

severe

low

frequency

transients,

or

DC

offset,

appearing

at

the

input

to

the

PC2002M

are

unlikely

to

damage

a

speaker

load.

Other

amplifiers

which

are

DC

coupled

throughout

may

have

a

"'flatter''

sub-audio

frequency

response,

but

this

makes

them

capable

of

ampli-

fying

dangerous

DC

input

voltage

or

sub-audio

transients

and

delivering

them

(at

high

power)

to

a

speaker.

POWER

BANDWIDTH

(Refer

to

Figure

4)

The

power

bandwidth

of

the

PC2002M

is

a

measure

of

its

ability

to

produce

high

power

output

over

a

wide

frequency

range.

The

limits

of

the

power

bandwidth

are

those

points

where

the

PC2002M

can

only

produce

1/2

the

power

that

it

can

produce

at

1000Hz.

While

the

frequency

response

is

measured

at

relatively

low

power

output

(1

watt),

the

power

bandwidth

is

measured

at

the

PC2002M's

full

power

output

(before

clipping).

The

power

bandwidth

of

the

PC2002M

is

quite

“Нат”,

and

extends

to

100kHz,

well

beyond

the

limits

of

the

audio

spectrum.

The

wide

power

bandwidth

of

the

PC2002M

means

that

it

can

reproduce

high

level

upper

harmonics

of

a

signal

as

easily

as

it

can

reproduce

mid-range

fundamentals.

It

means

that

you

get

full

power

performance

from

the

PC2002M

over

the

entire

audio

frequency

spectrum.

This

is

especially

important

when

the

amplifier

is

called

upon

to

reproduce

musical

material

with

high

energy

over

a

wide

frequency

range,

such

as

rock

and

roll.

CHANNEL

SEPARATION

This

specification

indicates

the

output

from

one

channel

when

a

signal

is

fed

to

the

other

channel.

The

PC2002M's

channel

separation

is

very

good,

which

means

that

even

critical

stereo

programs

will

be

unaffected

by

crosstalk

between

channels.

HUM

AND

NOISE

Hum

or

noise

from

a

power

amplifier

disrupts

a

program,

and

is

irritating

to

a

listener.

Hum

and

noise.

could

be

considered

a

form

of

distortion.

The

PC2002M's

hum

and

noise

are

so

low

that

they

are

completely

inaudible

under

any

normal

listening

circumstances.

SLEW

RATE

А

Slew

rate

is

a

measure

of

а

power

amplifier’s

ability

to

follow:

a

fast

rising

waveform

at

higher

frequencies

and

higher

power

outputs

than

the

rise

time

measurement.

It

might

seem

reasonable

to

assume

that

the

fastest

slew

rate

for

an

audio

waveform

occurs

at

20kHz.

However,

this

is

not

the

case.

When

one

frequency

is

superimposed

upon

another,

the

combined

waveform

has

a

slew

rate

that

is

greater

than

the

slew

rate

of

either

signal

by

itself.

The

actual

value

of

the

slew

rate

of

one

of

these

waveforms

(or

any

waveform)

depends

not

only

on

the

frequency,

but

on

the

amplitude

of

the

waveform

as

well.

Thus,

the

criteria

for

a

good

slew

rate

specification,

which

indicates

that

an

amplifier

can

reproduce

these

combination

waveforms,

varies

with

the

maximum

power

output

capability

of

the

amplifier.

The

higher

the

power,

the

higher

the

required

slew

rate.

With

a

60

volts/microsecond

slew

rate,

the

PC2002M

can

easily

reproduce

even

the

most

extreme

audio

waveforms

at

its

full

power

output.

INPUT

IMPEDANCE

The

input

impedance

of

the

PC2002M

is

high

enough

to

allow

it

to

be

used

with

most

semi-pro

devices,

or

to

be

used

as

a

“bridging”

load

for

а

600-ohm

source.

INPUT

SENSITIVITY

The

PC2002M's

input

sensitivity

indicates

the

input

drive

voltage

needed

for

the

PC2002M

to

produce

its

rated

output

of

240

watts

into

8

ohms

(input

attenuators

are

adjusted

to

maximum

clockwise

rotation

for

minimum

attenuation).

PROTECTION

CIRCUITS

AND

THERMAL

SPECIFICATIONS

The

PC2002M

is

one

of

the

safest

amplifiers

you

can

find.

It

incorporates

multiple

protection

circuits—transient

suppression,

current

limiting,

short

circuit

and

overload

protection,

dc

offset

sensing

with

relay

disconnect,

powered

transformer

overtemperature

sensing

with

auto

shutdown—

to

prevent

speaker

damage

in

the

event

of

an

amplifier

failure,

and

to

prevent

amplifier

damage

in

the

event

of

a

load

or

cable

problem.

Because

the

circuits

function

auto-

matically,

front

panel

LEDs

are

installed

to

inform

the

operator

of

overload

protection

status.

A

thermal

LED

also

warns

of

excessive

heat

sink

temperature.

GAIN

Gain

is

the

ratio

of

the

PC2002M's

output

voltage

to

its

input

voltage..

Maximum

gain

occurs

when

the

input

attenuators

are

set

for

minimum

attenuation.

If

the

input

and

output

voltage

are

specified

in

dB,

the

voltage

gain

is

equal

to

the

difference

of

the

two

dB

numbers.

As

stated

under

:

INPUT

SENSITIVITY,

an.

input

voltage

of

OdB

(0.775

volts)

produces

an

output

power

of

100

watts

into

an

8-ohm

load.